Differentiation of protonated aromatic regioisomers related to lignin by reactions with trimethylborate in a Fourier transform ion cyclotron resonance mass spectrometer.

Several lignin model compounds were examined to test whether gas-phase ion-molecule reactions of trimethylborate (TMB) in a FTICR can be used to differentiate the ortho-, meta-, and para-isomers of protonated aromatic compounds, such as those formed during degradation of lignin. All three regioisomers could be differentiated for methoxyphenols and hydroxyphenols. However, only the differentiation of the ortho-isomer from the meta- and para-isomers was possible for hydroxyacetophenones and hydroxybenzoic acids.

Static headspace gas chromatographic method for the determination of low and high boiling residual solvents in Betamethasone valerate.

Currently, there are no analytical methods available in the literature that can simultaneously separate and quantitate residual levels of acetone, methylene chloride, n-butyl ether and dimethylsulfoxide in Betamethasone valerate active pharmaceutical ingredient (API). This paper describes the development and validation of a simple, efficient, accurate and robust static headspace gas chromatography method for the determination of high and low boiling residual solvents, namely acetone, methylene chloride, n-butyl ether and dimethylsulfoxide, in Betamethasone valerate API. This method has been demonstrated to be accurate, linear, precise, reproducible, specific and robust for its intended purpose.

Identification and counting of carbonyl and hydroxyl functionalities in protonated bifunctional analytes by using solution derivatization prior to mass spectrometric analysis via ion-molecule reactions.

A mass spectrometric method has been developed for the identification of carbonyl and hydroxyl functional groups, as well as for counting the functional groups, in previously unknown protonated bifunctional oxygen-containing analytes. This method utilizes solution reduction before mass spectrometric analysis to convert the carbonyl groups to hydroxyl groups. Gas-phase ion-molecule reactions of the protonated reduced analytes with neutral trimethylborate (TMB) in a FT-ICR mass spectrometer give diagnostic product ions.

Evaluation of a novel approach for peptide sequencing: laser-induced acoustic desorption combined with P(OCH(3))(2)(+) chemical ionization and collision-activated dissociation in a Fourier transform ion cyclotron resonance mass spectrometer.

A novel mass spectrometric method has been developed for obtaining sequence information on small peptides. The peptides are desorbed as intact neutral molecules into a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR) by means of laser-induced acoustic desorption (LIAD). Reactions of the neutral peptides with the dimethoxyphosphenium ion, P(OCH(3))(2)(+), occur predominantly by addition of the peptide to P(OCH(3))(2)(+) followed by the loss of two methanol molecules, thus yielding product ions with the composition (peptide + P - 2H)(+).